Air circuit breaker



FIG. 1 is a perspective view of an air circuit breaker showing the new design:

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left-side elevation view thereof;

FIG. 5 is a right-side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines and the unshaded surfaces shown in the drawings illustrate portions of the air circuit breaker that form no part of the claimed design. 

CLAIM The ornamental design for an air circuit breaker, as shown and described. 